Electrostatic chuck, substrate fixing device and manufacturing method of electrostatic chuck

Abstract

An electrostatic chuck comprises: an insulating substrate having a mounting surface on which an adsorbed object is mounted and an opposite surface provided on the opposite side of the mounting surface; and a gas hole penetrating from the opposite surface to the mounting surface. The gas hole comprises a first hole portion extending from the opposite surface toward the mounting surface, a second hole portion extending from the mounting surface toward the opposite surface, and a third hole portion provided between the first hole portion and the second hole portion and formed to communicate with each other. The first hole portion is provided so as not to overlap with the second hole portion when viewed in a planar view.

Description

Technology Field

[0001] The present invention relates to an electrostatic chuck, a substrate fixing device, and a method for manufacturing an electrostatic chuck. Background Technology

[0002] Conventionally, when manufacturing semiconductor devices as ICs and LSIs, a film deposition device (e.g., CVD device, PVD device, etc.) and a plasma etching device are equipped with a stage for precisely holding a substrate (e.g., a silicon wafer) in a vacuum processing chamber. As such a stage, a substrate fixing device is proposed that is configured to adsorb and hold the wafer by, for example, an electrostatic chuck mounted on a base plate.

[0003] A substrate fixing device comprises, for example, a metal base plate, an electrostatic chuck bonded to the base plate, and an electrostatic electrode embedded in the electrostatic chuck. Additionally, the substrate fixing device comprises a gas supply unit for cooling a wafer. The gas supply unit supplies gas to the surface of the electrostatic chuck through a gas channel provided in the base plate and a gas hole provided in the electrostatic chuck (see, for example, Patent Document 1). Prior art literature

[0004] JP-A-2013-232640 The problem to be solved

[0005] In conventional substrate fixing devices, when a high-frequency power supply is applied to a metal base plate to generate plasma on the wafer surface while the wafer is placed on an electrostatic chuck, an abnormal electric discharge may occur in the gas supply section. means of solving the problem

[0006] One embodiment of the present disclosure relates to an electrostatic chuck. This electrostatic chuck is,

[0007] An insulating substrate having a placement surface on which an adsorbed object is placed and an opposite surface provided on the opposite side of the placement surface; and

[0008] It includes a gas hole penetrating from the opposite surface to the mortise surface, and

[0009] The gas hole includes a first hole portion extending from the opposite surface toward the mounting surface, a second hole portion extending from the mounting surface toward the opposite surface, and a third hole portion provided between the first hole portion and the second hole portion and formed to communicate with each other, and

[0010] The first hole is arranged so as not to overlap with the second hole when viewed in a planar view. Effects of the invention

[0011] According to one embodiment of the present invention, an effect of suppressing the occurrence of abnormal discharge can be obtained. Brief explanation of the drawing

[0012] FIG. 1a is a schematic cross-sectional view illustrating a substrate fixing device according to a first embodiment. FIG. 1b is an enlarged cross-sectional view showing a part of the substrate fixing device shown in FIG. 1a (a cross-sectional view taken along line 1b-1b of FIG. 2). FIG. 2 is a schematic plan view illustrating a part of a substrate fixing device according to a first embodiment. FIGS. 3a and 3b are schematic cross-sectional views illustrating a method for manufacturing an electrostatic chuck according to a first embodiment. FIGS. 4a and FIGS. 4b are schematic cross-sectional views illustrating a method for manufacturing an electrostatic chuck according to a first embodiment. FIGS. 5A and 5B are schematic cross-sectional views illustrating a method for manufacturing an electrostatic chuck according to a first embodiment. FIGS. 6a and 6b are schematic cross-sectional views illustrating a method for manufacturing an electrostatic chuck according to a first embodiment. FIGS. 7a and 7b are schematic cross-sectional views illustrating a method for manufacturing an electrostatic chuck according to a second embodiment. FIGS. 8A and FIGS. 8B are schematic cross-sectional views illustrating a method for manufacturing an electrostatic chuck according to a second embodiment. FIGS. 9A and 9B are schematic cross-sectional views illustrating a method for manufacturing an electrostatic chuck according to a second embodiment. FIGS. 10a and FIGS. 10b are schematic cross-sectional views illustrating a method for manufacturing an electrostatic chuck according to a third embodiment. FIGS. 11a and FIGS. 11b are schematic cross-sectional views illustrating a method for manufacturing an electrostatic chuck according to a third embodiment. FIGS. 12a and FIGS. 12b are schematic cross-sectional views illustrating a method for manufacturing an electrostatic chuck according to a third embodiment. FIG. 13 is a schematic cross-sectional view illustrating a substrate fixing device according to a modified embodiment. FIG. 14 is a schematic cross-sectional view illustrating a substrate fixing device according to a comparative example. Specific details for implementing the invention

[0013] Hereinafter, each embodiment will be described with reference to the attached drawings. Additionally, it should be noted that in the attached drawings, feature parts are illustrated in enlarged form for convenience to facilitate easy understanding of the features, and the dimensional ratios of each component may vary from drawing to drawing. Furthermore, in the cross-sectional views, the hatching of some members is shown in a satin form, and the hatching of some members is omitted to facilitate easy understanding of the cross-sectional structure of each member. Additionally, it should be noted that in this specification, "when viewed from a plane" means viewing the object from a vertical direction (up-down direction in the drawings), such as in FIG. 1a, and "planar shape" means the shape of the object viewed from a vertical direction, such as in FIG. 1a. In this specification, "up-down direction" and "left-right direction" are directions in which the direction in which the reference number representing each member in each drawing can be correctly read is considered the normal position.

[0014] (1st Example)

[0015] Hereinafter, a first embodiment will be described with reference to FIGS. 1a to 6b.

[0016] <Configuration of the substrate fixing device (10)>

[0017] As illustrated in FIG. 1a, the substrate fixing device (10) has a base plate (20) and an electrostatic chuck (30) disposed on the base plate (20). The electrostatic chuck (30) is attached to the upper surface of the base plate (20) by an adhesive such as silicone resin. For reference, the electrostatic chuck (30) may also be fixed to the base plate (20) by a screw. An adsorption target (not shown) is placed on the upper surface of the electrostatic chuck (30). The adsorption target is, for example, a substrate such as a semiconductor wafer. The substrate fixing device (10) is configured to adsorb and maintain the adsorption target placed on the electrostatic chuck (30).

[0018] (Composition of base plate (20))

[0019] The shape and size of the base plate (20) may be formed in any shape and size. The base plate (20) is formed in a disc shape to match the shape of the adsorption target placed on the electrostatic chuck (30), for example. The diameter of the base plate (20) may be, for example, about 150 mm to 500 mm. The thickness of the base plate (20) may be, for example, about 10 mm to 50 mm. Here, the term "disc shape" in this specification refers to a planar shape that is circular and has a predetermined thickness. For reference, the thickness relative to the diameter in the "disc shape" is not important. Additionally, a shape in which a partially concave or convex portion is formed is also assumed to be included in the "disc shape."

[0020] As the material for the base plate (20), metal materials such as aluminum or cemented carbide, or composite materials of metal and ceramic materials, may be used. In this embodiment, an aluminum or aluminum alloy surface that has undergone an anodizing treatment (forming an insulating layer) is used for ease of availability, ease of processing, and good thermal conductivity.

[0021] (Composition of gas flow path (21))

[0022] The base plate (20) has a gas passage (21) that penetrates the base plate (20) in the thickness direction (up and down direction in the drawing). Gas is supplied to the gas passage (21) to cool an adsorbed object placed on, for example, the electrostatic chuck (30). An inert gas may be used as the cooling gas. For example, helium (He) gas, argon (Ar) gas, etc. may be used as the inert gas. The gas passage (21) is formed by penetrating from the upper surface of the base plate (20) connected to the electrostatic chuck (30) to the lower surface on the opposite side of the upper surface.

[0023] The gas flow path (21) has a gas flow path section (22) formed on the lower surface of the base plate (20), a plurality of gas flow path sections (23) formed on the upper surface of the base plate (20), and a gas flow path section (24) configured to communicate with each other between the gas flow path section (22) and the gas flow path sections (23).

[0024] The gas flow channel (22) is formed to open downwards toward the base plate (20). The gas flow channel (22) is formed to extend, for example, from the lower surface of the base plate (20) toward the upper surface along the thickness direction of the base plate (20). The lower end of the gas flow channel (22) is an inlet (inlet) of the gas flow channel (21) into which inert gas is introduced from a gas supply source (not shown).

[0025] Each gas flow section (23) is formed to open upward toward the base plate (20). Each gas flow section (23) is formed to extend, for example, from the upper surface of the base plate (20) toward the lower surface along the thickness direction of the base plate (20). The upper end of each gas flow section (23) is an outlet (outlet) of the gas flow section (21) for discharging the inert gas introduced into the gas flow section (21). A plurality of gas flow sections (23) are provided spaced apart from each other in a plane direction perpendicular to the thickness direction of the base plate (20) in a cross-sectional view. A plurality of gas flow sections (23) are scattered on the upper surface of the base plate (20), for example, when viewed in a plane. The number of gas flow sections (23) can be appropriately determined as needed. For example, the number of gas flow sections (23) may be in the tens to hundreds.

[0026] The gas flow section (24) is formed to connect, for example, a gas flow section (22) and a plurality of gas flow sections (23). The gas flow section (24) is formed such that, for example, one gas flow section (22) branches into a plurality of gas flow sections (23). The gas flow section (24) has, for example, a flow section (24A) extending in a planar direction from the upper end of the gas flow section (22), a flow section (24B) extending in the thickness direction of the base plate (20) from the end of the flow section (24A), and a flow section (24C) extending in a planar direction from the upper end of the flow section (24B). In this embodiment, the flow section (24C) extends to the left from the upper end of the flow section (24B) in the drawing and extends to the right from the upper end of the flow section (24B) in the drawing. The flow section (24C) is formed in an annular shape when viewed in a planar direction, for example. The Euro section (24C) is configured to communicate with the lower sections of the plurality of gas flow sections (23).

[0027] (Composition of the electrostatic chuck (30))

[0028] The electrostatic chuck (30) comprises an insulating substrate (40) and an electrostatic electrode (70) embedded in the insulating substrate (40).

[0029] (Composition of the insulating substrate (40))

[0030] The shape and size of the insulating substrate (40) can be formed in any shape and size. The insulating substrate (40) is formed in a disc shape to match, for example, the shape of the adsorption target placed on the electrostatic chuck (30). The planar shape of the insulating substrate (40) is formed to have the same shape and size as, for example, the planar shape of the base plate (20). The diameter of the insulating substrate (40) may be, for example, about 150 mm to 500 mm. The thickness of the insulating substrate (40) may be, for example, about 1 mm to 5 mm. Note that the size of the planar shape of the insulating substrate (40) may be smaller than the size of the planar shape of the base plate (20).

[0031] As a material for the insulating substrate (40), a material having insulating properties may be used. For example, as a material for the insulating substrate (40), ceramics such as aluminum oxide (Al2O3), aluminum nitride (AlN), and silicon nitride, and organic materials such as silicone resin and polyimide resin may be used. In this embodiment, ceramics such as aluminum oxide and aluminum nitride are used as the material for the insulating substrate (40) from the perspective of ease of availability, ease of processing, and relatively high plasma resistance. That is, the insulating substrate (40) of this embodiment is a ceramic substrate made of ceramics.

[0032] The insulating substrate (40) has a structure in which insulating layers (41, 42, and 43) of a plurality of layers (here, three layers) are stacked. Each insulating layer (41, 42, and 43) is a sintered body formed by sintering a green sheet, for example, a mixture of aluminum oxide and an organic material. In each drawing, the interface between insulating layer (41) and insulating layer (42) and the interface between insulating layer (42) and insulating layer (43) are shown as solid lines. These interfaces are formed by stacking a plurality of green sheets, and depending on the stacked state, the positions may differ, the interfaces may not be straight lines in cross-section, or the interfaces may not be clear.

[0033] The insulating substrate (40) has a placement surface (40A) on which an adsorbent object is placed, and an opposite surface (40B) provided on the opposite side of the placement surface (40A). The placement surface (40A) is provided, for example, on the upper surface of the insulating layer (43). A plurality of embosses (44) are formed on the placement surface (40A). The plurality of embosses (44) are installed side by side, for example, along the planar direction of the insulating substrate (40). The plurality of embosses (44) are formed, for example, by providing a plurality of concave portions (45) that are concave from the upper surface of the insulating layer (43) toward the base plate (20). Each concave portion (45) is formed to extend from the upper surface of the insulating layer (43) to a middle portion in the thickness direction of the insulating layer (43). The opposite surface (40B) is provided, for example, on the lower surface of the insulating layer (41). The opposite surface (40B) is bonded to, for example, the upper surface of the base plate (20).

[0034] (Composition of the gas hole (50))

[0035] The insulating substrate (40) has a gas hole (50) penetrating from the opposite surface (40B) of the insulating substrate (40) to the mounting surface (40A). The insulating substrate (40) has a plurality of gas holes (50). The plurality of gas holes (50) are provided corresponding to each of the plurality of gas flow sections (23). The plurality of gas holes (50) are formed to communicate with each of the plurality of flow sections (23). For example, an inert gas for cooling an adsorbed object mounted on the mounting surface (40A) is introduced into each gas hole (50). For example, the inert gas is introduced from each gas flow section (23) to each gas hole (50).

[0036] Each gas hole (50) is provided with a hole portion (51) extending from the opposite surface (40B) toward the mounting surface (40A), a hole portion (52) extending from the mounting surface (40A) toward the opposite surface (40B), and a hole portion (53) provided between the hole portion (51) and the hole portion (52) and formed to connect the hole portion (51) and the hole portion (52).

[0037] (Composition of the hole portion (51))

[0038] The hole portion (51) is formed to open downwards from the insulating substrate (40). The hole portion (51) is formed to communicate with the gas flow path (21), specifically the gas flow path portion (23). The hole portion (51) is formed to extend from the opposite surface (40B) of the insulating substrate (40), for example, along the thickness direction (up-down direction of the drawing) of the insulating substrate (40). The hole portion (51) is formed to extend linearly along the thickness direction of the insulating substrate (40). The hole portion (51) is formed to penetrate, for example, the insulating layer (41) in the thickness direction. The upper end of the hole portion (51) is formed to communicate with the hole portion (53). The shape and size of the hole portion (51) can be formed in any shape and size.

[0039] As illustrated in FIG. 2, the planar shape of the hole portion (51) in this embodiment is circular. The planar shape of the hole portion (51) is formed to be smaller than the planar shape of the hole portion (53). That is, the hole portion (51) is a smaller hole than the hole portion (53). The hole portion (51) overlaps entirely with the hole portion (53), for example, when viewed from a planar perspective.

[0040] (Composition of the hole portion (52))

[0041] As illustrated in FIG. 1b, the hole portion (52) is formed to open upward above the insulating substrate (40). The hole portion (52) is formed to extend, for example, from the mounting surface (40A) of the insulating substrate (40) along the thickness direction of the insulating substrate (40). The hole portion (52) is formed to extend linearly along the thickness direction of the insulating substrate (40). The hole portion (52) is formed to penetrate, for example, the insulating layer (43) in the thickness direction. The lower end of the hole portion (52) is formed to communicate with the hole portion (53). The upper end of the hole portion (52) is an outlet of the gas hole (50) for discharging inert gas to the outside of the gas hole (50). The shape and size of the hole portion (52) can be formed in any shape and size.

[0042] As illustrated in FIG. 2, the planar shape of the hole portion (52) in this embodiment is circular. The planar shape of the hole portion (52) is formed to be smaller than the planar shape of the hole portion (53). That is, the hole portion (52) is a smaller hole than the hole portion (53). The opening width (opening diameter) of the hole portion (52) may be the same as or different from the opening width (opening diameter) of the hole portion (51). For example, the opening width of the hole portion (52) may be smaller than the opening width of the hole portion (51). The hole portion (52) overlaps entirely with the hole portion (53) when viewed, for example, in a planar view.

[0043] (Composition of the hole portion (53))

[0044] As illustrated in FIG. 1b, a hole portion (53) is provided between a hole portion (51) and a hole portion (52) in the thickness direction of the insulating substrate (40). The hole portion (53) is formed to extend in the planar direction of the insulating substrate (40). The hole portion (53) is provided, for example, in the insulating layer (42). The hole portion (53) is provided to penetrate, for example, the insulating layer (42) in the thickness direction. A portion of the lower end of the hole portion (53) is formed to communicate with the hole portion (51). A portion of the upper end of the hole portion (53) is formed to communicate with the hole portion (52). The shape and size of the hole portion (53) can be formed in any shape and size.

[0045] As illustrated in FIG. 2, the planar shape of the hole portion (53) of the present embodiment is circular. The planar shape of the hole portion (53) is formed to be larger than the planar shapes of the hole portions (51 and 52). For example, the planar shape of the hole portion (53) is formed to be at least twice as large as the planar shape of each of the hole portions (51 and 52). For example, the diameter of the hole portion (53) may be about 5 mm to 6 mm, the diameter of the hole portion (51) may be about 2 mm to 3 mm, and the diameter of the hole portion (52) may be about 2 mm to 3 mm.

[0046] (Positional relationship of the holes (51, 52 and 53))

[0047] As illustrated in FIGS. 1B and FIGS. 2, the hole portion (51) and the hole portion (52) are arranged so that they do not overlap each other when viewed in a plane. The hole portion (51) is arranged so that the entire hole portion (51) does not overlap with the hole portion (52) when viewed in a plane. When viewed in a plane, the entire hole portion (51) overlaps with the hole portion (53), and the entire hole portion (52) overlaps with the hole portion (53). The hole portion (51) is arranged, for example, near the inner circumference of the hole portion (53) when viewed in a plane. The hole portion (51) is arranged so that, for example, when viewed in a plane, a part of the inner circumference of the hole portion (51) overlaps with a part of the inner circumference of the hole portion (53). The hole portion (52) is arranged, for example, near the inner circumference of the hole portion (53). The hole portion (52) is provided such that, for example, when viewed in a plane, a portion of the inner surface of the hole portion (52) overlaps with a portion of the inner surface of the hole portion (53). The hole portion (51) and the hole portion (52) are provided at positions furthest apart from each other within the range where, for example, when viewed in a plane, the entire hole portions (51 and 52) overlap with the hole portion (53). Here, the inner surface of the hole portion (53) has a first portion (53A) and a second portion (53B) arranged point-symmetrically with respect to the first portion (53A) with respect to the central axis (A1) of the hole portion (53). The central axis (A1) penetrates the planar center of the hole portion (53) and also extends along the thickness direction of the insulating substrate (40). In this embodiment, when viewed in a plane, a portion of the inner circumference of the hole portion (51) overlaps with the first portion (53A), and when viewed in a plane, a portion of the inner circumference of the hole portion (52) overlaps with the second portion (53B). Because of this, the distance between the inner circumferences that are furthest apart from each other in the hole portions (51 and 52) is the distance between the first portion (53A) and the second portion (53B) in the plane direction, that is, it is equal to the diameter of the hole portion (53).

[0048] As illustrated in FIG. 1b, in the portion where the inner surfaces of the holes (51 and 53) overlap when viewed in a planar view, the inner surface of the hole (51) and the inner surface of the hole (53) (i.e., the first portion (53A)) are formed to extend continuously in the thickness direction of the insulating substrate (40). Additionally, in the portion where the inner surfaces of the holes (52 and 53) overlap when viewed in a planar view, the inner surface of the hole (52) and the inner surface of the hole (53) (i.e., the second portion (53B)) are formed to extend continuously in the thickness direction of the insulating substrate (40).

[0049] The gas hole (50) is formed in a crank shape when viewed in cross-section. The cross-sectional shape of the gas hole (50) has a crank shape with two bends. That is, the cross-sectional shape of the gas hole (50) has a crank shape composed of a hole portion (51) extending upward from the opposite surface (40B), a hole portion (53) extending in a planar direction from the upper part of the hole portion (51), and a hole portion (52) extending upward from the hole portion (53) at a position offset from the hole portion (51) when viewed in a planar view. In the gas hole (50), an inert gas is introduced into the hole portion (51) through the gas flow path (21), and an inert gas flows into the hole portion (53) through the hole portion (51). Additionally, in the gas hole (50), the inert gas introduced into the hole portion (53) moves in a planar direction within the hole portion (53) and then enters the hole portion (52), and this inert gas is discharged from the gas hole (50) through the hole portion (52). The inert gas discharged from the hole portion (52) is filled, for example, between the lower surface of the adsorption target placed on the placement surface (40A) and the placement surface (40A), thereby cooling the adsorption target.

[0050] (Composition of porous body (60))

[0051] A porous body (60) having breathability is provided in the gas hole (50). The porous body (60) is provided, for example, in the hole portion (53) of the gas hole (50). The porous body (60) has holes within the porous body (60). These holes communicate with the hole portions (51 and 52), so that gas can pass from the lower side (hole portion (51) side) of the porous body (60) toward the upper side (hole portion (52) side) of the porous body (60). The porous body (60) is formed, for example, by providing a number of ceramic beads, such as alumina beads, in the hole portion (53). For the porous body (60), for example, glass fiber, heat-resistant resin sponge, etc., can be used. For example, the porous body (60) is not provided in the hole portions (51 and 52).

[0052] (Composition of electrostatic electrode (70))

[0053] As illustrated in FIG. 1a, an electrostatic electrode (70) is provided on an insulating substrate (40). The electrostatic electrode (70) is, for example, a conductive layer formed in the shape of a film. The electrostatic electrode (70) is provided, for example, on a portion of the insulating substrate (40) located near the mounting surface (40A). The electrostatic electrode portion (70) is, for example, formed on the upper surface of an insulating layer (42). The electrostatic electrode (70) is provided to be sandwiched, for example, between an insulating layer (42) and an insulating layer (43). The electrostatic electrode (70) is electrically connected, for example, to an adsorption power source (not shown). The electrostatic electrode (70) is configured to fix an object to be adsorbed to the mounting surface (40A) by an electrostatic force generated by a voltage applied from the adsorption power source. For example, tungsten (W) or molybdenum (Mo) can be used as the material for the electrostatic electrode (70). Note that although one electrostatic electrode (70) is shown in FIG. 1a, in reality, multiple electrodes are included that are placed on the same plane.

[0054] (actions)

[0055] Next, the operations of the substrate fixing device (10) will be described.

[0056] For example, with the substrate fixing device (10) placed in the chamber (not shown), an adsorption target is placed on the placement surface (40A) of the electrostatic chuck (30). By introducing a raw material gas into the chamber and applying a high-frequency voltage to the base plate (20), plasma is generated to perform processing on the adsorption target (e.g., a wafer). At this time, an inert gas, such as He gas, is introduced from a gas source (not shown) into a gas supply unit composed of a gas passage (21) and a gas hole (50). The inert gas passes sequentially through the gas passage (21), the hole portion (51) of the gas hole (50), the porous body (60) inside the hole portion (53), and the hole portion (52), and is supplied to the lower surface of the adsorption target placed on the placement surface (40A). When plasma is generated in this manner, an abnormal discharge may occur between the adsorption target and the metal base plate (20). As an example of a path for abnormal discharge, as illustrated in FIG. 1b, path R1 can be given from the upper part of the inert gas outlet of the gas hole (50), i.e., the hole portion (52), to the base plate (20) passing through the inside of the gas hole (50). Path R1 is, for example, the shortest path from the upper part of the hole portion (52) through the inside of the gas hole (50) to the upper surface of the base plate (20).

[0057] Here, as in the comparative example shown in FIG. 14, if a path R2 extending linearly along the thickness direction of the insulating substrate (40C) (electrostatic chuck (30C)) from the outlet (50D) of the gas hole (50C) to the upper surface of the base plate (20) exists in the gas hole (50C), the length of the path R2 matches the thickness of the insulating substrate (40C). That is, the length of the abnormal discharge path R2 matches the dimension in the thickness direction of the insulating substrate (40C).

[0058] In contrast, as illustrated in FIG. 1b, in the electrostatic chuck (30) of the present embodiment, the hole portion (51) formed on the opposite surface (40B) of the insulating substrate (40) and the hole portion (52) formed on the mounting surface (40A) are arranged so as not to overlap each other when viewed in a planar view. According to this configuration, the upper portion of the hole portion (52) which serves as the outlet of the gas hole (50) and the lower portion of the hole portion (51) which opens on the upper surface side of the base plate (20) can be offset in the planar direction. Because of this, the length of the abnormal discharge path R1 can be longer than the thickness of the insulating substrate (40) by the amount of offset of the holes (51 and 52) in the planar direction. Specifically, in the electrostatic chuck (30) of the present embodiment, the path R1 extends from the upper portion of the hole portion (52) to the lower portion of the hole portion (52) along the thickness direction of the insulating layer (43). Path R1 extends, for example, from the lower end of the hole portion (52) to the upper end of the hole portion (51) in the hole portion (53). At this time, since the hole portion (51) and the hole portion (52) are arranged to be offset from each other when viewed in a plane, the shortest path from the lower end of the hole portion (52) to the upper end of the hole portion (51) extends in an oblique direction intersecting the thickness direction of the insulating layer (42). Because of this, the length of path R1 in the hole portion (53) becomes longer than the thickness of the insulating layer (42). Path R1 extends from the upper end of the hole portion (51) to the upper surface of the base plate (20) along the thickness direction of the insulating layer (41). In this way, the length of path R1 becomes longer than the thickness of the insulating layers (41 to 43) (insulating substrate (40)) and longer than path R2 of the comparative example (see FIG. 14). Accordingly, compared to the comparative example, the possibility of collision between the plasma remaining in the gas hole (50) and the inert gas can be reduced. As a result, the occurrence of abnormal discharge can be effectively suppressed, and the occurrence of insulation breakdown due to abnormal discharge can be effectively suppressed.

[0059] <Method for manufacturing a substrate fixing device (10)>

[0060] Next, the manufacturing method of the substrate fixing device (10) will be described. Here, the manufacturing method of the electrostatic chuck (30) will be described in detail.

[0061] First, in the process illustrated in FIG. 3a, green sheets (81, 82, and 83) made of ceramic material and organic material are prepared. Each of the green sheets (81, 82, and 83) has a sheet shape, for example, made by mixing aluminum oxide (alumina) with a binder, solvent, etc. The size of the planar shape of each green sheet (81, 82, and 83) corresponds to the size of the planar shape of the insulating substrate (40) illustrated in FIG. 1a.

[0062] The green sheet (83) becomes the insulating layer (43) shown in FIG. 1a by being fired in a process described later. The green sheet (83) has a through hole (83X) that penetrates the green sheet (83) in the thickness direction. The through hole (83X) is provided at a position corresponding to the hole portion (52) shown in FIG. 1a. The size of the planar shape of the through hole (83X) is formed to be smaller than the size of the planar shape of the hole portion (52) shown in FIG. 1a. The green sheet (82) becomes the insulating layer (42) shown in FIG. 1a by being fired in a process described later. The green sheet (82) has a through hole (82X) that penetrates the green sheet (82) in the thickness direction. The through hole (82X) is provided at a position corresponding to the hole portion (53) shown in FIG. 1a. The size of the planar shape of the through hole (82X) is set to correspond to the size of the planar shape of the hole portion (53) shown in FIG. 1a. The green sheet (81) becomes the insulating layer (41) shown in FIG. 1a by being fired in the process described later. No through holes are formed in the green sheet (81). For reference, the through holes (82X and 83X) are formed, for example, by laser machining or machining.

[0063] Next, in the process illustrated in FIG. 3b, the green sheets (81, 82, and 83) are compressed in the thickness direction by heating and pressing the green sheets (81, 82, and 83). Through this process, the thickness direction dimensions of each green sheet (81, 82, and 83) become smaller than the dimensions prior to this process. By compressing each green sheet (81, 82, and 83) in the thickness direction in this way, the amount of shrinkage of each green sheet (81, 82, and 83) can be stably controlled when each green sheet (81, 82, and 83) is fired in the process described later.

[0064] Next, in the process illustrated in FIG. 4a, a conductive pattern (71) is formed on the upper surface of a green sheet (82) using a conductive paste, for example, by a printing method (screen printing). The conductive pattern (71) becomes an electrostatic electrode (70) shown in FIG. 1a by being fired in a process described later. For reference, as the conductive paste, a paste containing metal particles such as molybdenum, conductive ceramic particles, a binder, and a solvent may be used. Note that the conductive pattern (71) may also be formed on the lower surface of the green sheet (83).

[0065] Additionally, in the process illustrated in FIG. 4a, a green sheet (82) is placed on a green sheet (81) with the surface on which the conductor pattern (71) is formed facing upward. Then, the green sheets (81 and 82) are stacked. The green sheets (81 and 82) are bonded together, for example, by applying pressure while heating them. By this process, the opening on the lower side of the through hole (82X) of the green sheet (82) is closed by the green sheet (81).

[0066] Next, in the process illustrated in FIG. 4b, a paste material (61), which is a precursor of the porous body (60) illustrated in FIG. 1a, is filled into the through hole (82X) using a squeegee or the like. At this time, since the opening on one side (here, the lower side) of the through hole (82X) is closed by the green sheet (81), the paste material (61) can be easily filled into the through hole (82X). The paste material (61) includes, for example, ceramic beads such as alumina beads that constitute the porous body (60) illustrated in FIG. 1a. As the paste material (61), a material including, for example, alumina beads, a binder, and a solvent may be used.

[0067] Next, in the process illustrated in FIG. 5a, a green sheet (83) is placed on the green sheets (81 and 82) with the green sheet (82) positioned on the upper side. At this time, the green sheets (81, 82 and 83) are positioned so that, when viewed in a plane, the through hole (83X) overlaps with the through hole (82X). Then, the green sheets (81, 82 and 83) are stacked to form a structure (80). The green sheets (81, 82 and 83) are joined together, for example, by applying pressure while heating them. By this process, a conductive pattern (71) is embedded between the green sheet (82) and the green sheet (83), and the through hole (83X) and the through hole (82X) are connected to each other.

[0068] Next, in the process illustrated in FIG. 5b, the structure (80) illustrated in FIG. 5a is sintered. By doing so, the green sheets (81, 82 and 83) are sintered to form respective insulating layers (41, 42 and 43), and a ceramic substrate (80A) is formed in which the insulating layers (41, 42 and 43) are laminated. The temperature during sintering is, for example, 1500°C to 1600°C. By sintering in this process, organic components such as solvents of the paste material (61) shown in FIG. 5a volatilize, and the alumina beads of the paste material (61) are sintered. By doing so, a plurality of alumina beads are provided in the through hole (82X), and a porous body (60) is formed within the through hole (82X). At this time, since a through hole (83X) is formed in the insulating layer (43), the gas generated by the volatilization of the organic component of the paste material (61) can be effectively discharged to the outside of the ceramic substrate (80A) through the through hole (83X). By doing so, the insulating layers (41 and 43) can be effectively suppressed from being deformed and expanding outward by the aforementioned gas. For reference, the ceramic substrate (80A) has an electrostatic electrode (70) inside, which is obtained by sintering the conductor pattern (71) shown in FIG. 5a. Various treatments are performed on the ceramic substrate (80A).

[0069] Next, in the process illustrated in FIG. 6a, a through hole (81X) is formed that penetrates the insulating layer (41) in the thickness direction and communicates with the through hole (82X), and a through hole (83Y) is formed that penetrates the insulating layer (43) in the thickness direction and communicates with the through hole (82X). Here, the through hole (81X) corresponds to the hole portion (51), the through hole (82X) corresponds to the hole portion (53), and the through hole (83Y) corresponds to the hole portion (52). By this, a gas hole (50) having through holes (81X, 82X and 83Y) is formed in the ceramic substrate (80A). The through hole (83Y) is formed to increase the opening width of the through hole (83X), for example, illustrated in FIG. 5b. The through hole (81X) is formed so as not to overlap with the through hole (83Y) when viewed in a planar view. For reference, through holes (81X and 83Y) are formed, for example, by laser machining or machining.

[0070] Next, in the process illustrated in FIG. 6b, both the upper and lower surfaces of the ceramic substrate (80A) are polished. By doing so, the upper surface of the ceramic substrate (80A) is formed as a substrate surface (40A). Next, a plurality of concaves (45) are formed on the substrate surface (40A), and embosses (44) are formed on the substrate surface (40A). By doing so, the insulating substrate (40) illustrated in FIG. 1a is obtained. For reference, the concaves (45) are formed, for example, by laser machining or machining.

[0071] By the above manufacturing process, an electrostatic chuck (30) can be manufactured.

[0072] In the present embodiment, the insulating layer (41) is an example of a first insulating layer, the insulating layer (42) is an example of a second insulating layer, the insulating layer (43) is an example of a third insulating layer, the hole portion (51) is an example of a first hole portion, the hole portion (52) is an example of a second hole portion, and the hole portion (53) is an example of a third hole portion. Also, the green sheet (81) is an example of a first green sheet, the green sheet (82) is an example of a second green sheet, and the green sheet (83) is an example of a third green sheet. Also, the through hole (82X) is an example of a first through hole, the through hole (81X) is an example of a second through hole, the through hole (83Y) is an example of a third through hole, and the through hole (83X) is an example of a fourth through hole.

[0073] (effect)

[0074] Next, the effects of the present embodiment will be explained.

[0075] (1) A hole portion (51) extending from the opposite surface (40B) of the insulating substrate (40) toward the mounting surface (40A) and a hole portion (52) extending from the mounting surface (40A) toward the opposite surface (40B) are arranged so as not to overlap each other when viewed in a planar view. According to this configuration, the upper portion of the hole portion (52) which serves as the outlet of the gas hole (50) and the lower portion of the hole portion (51) which opens on the upper surface side of the base plate (20) can be offset in the planar direction. Because of this, the length of the abnormal discharge path R1 can be longer than the thickness of the insulating substrate (40) by the amount of offset of the holes (51 and 52) in the planar direction. By doing so, the possibility of collision between the plasma remaining in the gas hole (50) and the inert gas can be reduced. As a result, the occurrence of abnormal discharge can be effectively suppressed, and the occurrence of insulation breakdown due to abnormal discharge can be effectively suppressed.

[0076] (2) The planar shape of the hole portion (53) is formed to be larger than the planar shape of the hole portions (51 and 52). According to this configuration, the amount of offset in the planar direction of the hole portion (51) and the hole portion (52) can be easily increased when viewed from a plane and overlapped with the hole portion (53). By doing so, the length of the abnormal discharge path R1 can be easily increased.

[0077] (3) The hole portion (51) is arranged so that, when viewed in a plane, the entire hole portion (51) overlaps with the hole portion (53) and a part of the inner circumference of the hole portion (51) overlaps with the first part (53A) of the inner circumference of the hole portion (53). Additionally, the hole portion (52) is arranged so that, when viewed in a plane, the entire hole portion (52) overlaps with the hole portion (53) and a part of the inner circumference of the hole portion (52) overlaps with the second part (53B) of the inner circumference of the hole portion (53). According to this configuration, the hole portion (51) and the hole portion (52) can be arranged at positions furthest apart from each other within the range where the entire hole portions (51 and 52) overlap with the hole portion (53) when viewed in a plane. By doing so, the amount of offset between the hole portion (51) and the hole portion (52) in the plane direction can be increased, thereby increasing the length of the abnormal discharge path R1. Therefore, the occurrence of abnormal discharge can be suppressed more effectively.

[0078] (4) A porous body (60) is provided in the hole portion (53). By doing so, plasma can be suppressed from remaining in the gas hole (50), particularly in the hole portion (53). As a result, the possibility of collision between the plasma remaining in the gas hole (50) and the inert gas can be reduced, thereby suppressing the occurrence of abnormal discharge.

[0079] (2nd Example)

[0080] Hereinafter, a second embodiment will be described with reference to FIGS. 7a to 9b. In this embodiment, the method of manufacturing the electrostatic chuck (30) is different from that of the first embodiment. Hereinafter, the differences from the first embodiment will be mainly described. The same reference numbers are assigned to components identical to those shown in FIGS. 1 to 6, and detailed descriptions of each component are omitted.

[0081] First, in the process illustrated in FIG. 7a, a green sheet (81) having a through hole (81X), a green sheet (82) having a through hole (82X), and a green sheet (83) having a through hole (83Y) are prepared. Here, the through hole (81X) is provided at a position corresponding to the hole portion (51) illustrated in FIG. 1a. The size of the planar shape of the through hole (81X) is set to correspond to the size of the planar shape of the hole portion (51) illustrated in FIG. 1a. The through hole (83Y) is provided at a position corresponding to the hole portion (52) illustrated in FIG. 1a. The size of the planar shape of the through hole (83Y) is set to correspond to the size of the planar shape of the hole portion (52) illustrated in FIG. 1a. The through hole (81X) and the through hole (83Y) are formed at positions that do not overlap each other when viewed in a plane.

[0082] Next, in the process illustrated in FIG. 7b, each green sheet (81, 82, and 83) is compressed in the thickness direction by heating and pressing each green sheet (81, 82, and 83).

[0083] Next, in the process illustrated in FIG. 8a, a conductive pattern (71) is formed on the upper surface of the green sheet (82), for example, by screen printing. For reference, the conductive pattern (71) may also be formed on the lower surface of the green sheet (83).

[0084] Additionally, in the process illustrated in FIG. 8a, a green sheet (82) is placed on a green sheet (81) with the surface on which the conductor pattern (71) is formed facing upward. At this time, the green sheets (81 and 82) are positioned so that, when viewed in a plane, the through hole (81X) overlaps with the through hole (82X). Then, the green sheets (81 and 82) are stacked.

[0085] Next, in the process illustrated in FIG. 8b, paste material (71) is filled into the through hole (82X).

[0086] Next, in the process illustrated in FIG. 9a, a green sheet (83) is placed on the green sheets (81 and 82) with the green sheet (82) positioned on the upper side. At this time, the green sheets (81, 82 and 83) are positioned such that, when viewed in a plane, the through hole (83Y) overlaps with the through hole (82X), and when viewed in a plane, the through hole (83Y) does not overlap with the through hole (81X). Then, the green sheets (81, 82 and 83) are stacked to form a structure (80).

[0087] Next, in the process illustrated in FIG. 9b, the structure (80) illustrated in FIG. 9a is sintered. By doing so, the green sheets (81, 82 and 83) are sintered to form respective insulating layers (41, 42 and 43), and a ceramic substrate (80A) is formed in which the insulating layers (41, 42 and 43) are stacked. By sintering in this process, organic components such as solvents of the paste material (61) shown in FIG. 9a volatilize, and the alumina beads of the paste material (61) are sintered. By doing so, a porous body (60) having a plurality of alumina beads in the through hole (82X) is formed. At this time, since through holes (81X and 83Y) are formed in the insulating layers (41 and 43), gas generated by the volatilization of the organic component of the paste material (61) can be effectively discharged to the outside of the ceramic substrate (80A) through the through holes (81X and 83Y). By doing so, the insulating layers (41 and 43) can be effectively suppressed from being deformed by the aforementioned gas and expanding outward. By this process, a gas hole (50) having through holes (81X, 82X and 83Y) is formed in the ceramic substrate (80A). At this time, the through hole (81X) corresponds to the hole portion (51), the through hole (82X) corresponds to the hole portion (53), and the through hole (83Y) corresponds to the hole portion (52).

[0088] After that, both the upper and lower surfaces of the ceramic substrate (80A) are polished. By doing so, the upper surface of the ceramic substrate (80A) is formed into a substrate surface (40A). Next, a plurality of concave portions (45) are formed on the substrate surface (40A), and embosses (44) are formed on the substrate surface (40A). By doing so, an insulating substrate (40) and an electrostatic chuck (30) can be manufactured.

[0089] According to the above-described embodiment, the same effect as the effect (1) to (4) of the first embodiment can be obtained.

[0090] (Third Example)

[0091] Hereinafter, a third embodiment will be described with reference to FIGS. 10a to 12b. In this embodiment, the method of manufacturing the electrostatic chuck (30) is different from that of the first embodiment. Hereinafter, the differences from the first embodiment will be mainly described. The same reference numbers are assigned to components identical to those shown in FIGS. 1 to 9, and detailed descriptions of each component are omitted.

[0092] First, in the process illustrated in FIG. 10a, a green sheet (81), a green sheet (82) having a through hole (82X), and a green sheet (83) are prepared. Here, the green sheets (81 and 83) do not have through holes formed therein.

[0093] Next, in the process illustrated in FIG. 10b, each green sheet (81, 82, and 83) is compressed in the thickness direction by heating and pressing each green sheet (81, 82, and 83).

[0094] Next, in the process illustrated in FIG. 11a, a conductive pattern (71) is formed on the upper surface of the green sheet (82), for example, by screen printing. For reference, the conductive pattern (71) may also be formed on the lower surface of the green sheet (83).

[0095] Next, a green sheet (82) is laminated onto a green sheet (81) with the surface having the conductor pattern (71) formed facing upward.

[0096] Next, the paste material (61) is filled into the through hole (82X). At this time, since the opening on one side (here, the lower side) of the through hole (82X) is closed by the green sheet (81), the paste material (61) can be easily filled into the through hole (82X).

[0097] Next, in the process illustrated in FIG. 11b, a green sheet (83) is placed on the green sheets (81 and 82) with the green sheet (82) placed on the upper side. Then, the green sheets (81, 82 and 83) are stacked to form a structure (80).

[0098] Next, in the process illustrated in FIG. 12a, the structure (80) illustrated in FIG. 11b is sintered. By doing so, the green sheets (81, 82 and 83) are sintered to form respective insulating layers (41, 42 and 43), and a ceramic substrate (80A) is formed in which the insulating layers (41, 42 and 43) are laminated. By the sintering of this process, a porous body (60) is formed in the through hole (82X) from the paste material (61) shown in FIG. 11b.

[0099] Next, in the process illustrated in FIG. 12b, a through hole (81X) is formed that penetrates the insulating layer (41) in the thickness direction and communicates with the through hole (82X), and a through hole (83Y) is formed that penetrates the insulating layer (43) in the thickness direction and communicates with the through hole (82X). Here, the through hole (81X) corresponds to the hole portion (51), the through hole (82X) corresponds to the hole portion (53), and the through hole (83Y) corresponds to the hole portion (52). By this, a gas hole (50) having through holes (81X, 82X and 83Y) is formed in the ceramic substrate (80A).

[0100] After that, both the upper and lower surfaces of the ceramic substrate (80A) are polished. By doing so, the upper surface of the ceramic substrate (80A) is formed into a substrate surface (40A). Next, a plurality of concave portions (45) are formed on the substrate surface (40A), and embosses (44) are formed on the substrate surface (40A). By doing so, an insulating substrate (40) and an electrostatic chuck (30) can be manufactured.

[0101] According to the above-described embodiment, the same effect as the effect (1) to (4) of the first embodiment can be obtained.

[0102] (Other embodiments)

[0103] Each of the above embodiments may be modified and implemented as follows. Each of the above embodiments and the following modified embodiments may be implemented in combination within a technically consistent scope.

[0104] In each of the above embodiments, the hole portion (51) is provided such that a portion of the inner surface of the hole portion (51) overlaps with the first portion (53A) of the inner surface of the hole portion (53) when viewed from a plane. However, the formation location of the hole portion (51) is not particularly limited.

[0105] For example, as shown in FIG. 13, the hole portion (51) may be positioned so that it overlaps with the hole portion (53) when viewed in a plane and is spaced apart from the inner surface of the hole portion (53).

[0106] In each of the above embodiments, the hole portion (52) is provided such that a portion of the inner surface of the hole portion (52) overlaps with a second portion (53B) of the inner surface of the hole portion (53) when viewed from a plane. However, the location of the hole portion (52) is not particularly limited.

[0107] For example, as shown in FIG. 13, the hole portion (52) may be provided at a position that overlaps with the hole portion (53) and is spaced apart from the inner surface of the hole portion (53) when viewed in a planar view.

[0108] In each of the above embodiments, the entire hole portion (51) is arranged to overlap with the hole portion (53) when viewed in a planar view. However, the present invention is not limited thereto. For example, only a part of the hole portion (51) may overlap with the hole portion (53) when viewed in a planar view. That is, the hole portion (51) and the hole portion (53) may be arranged to partially overlap each other when viewed in a planar view.

[0109] In each of the above embodiments, the entire hole portion (52) is arranged to overlap with the hole portion (53) when viewed in a planar view. However, the present invention is not limited thereto. For example, only a part of the hole portion (52) may overlap with the hole portion (53) when viewed in a planar view. That is, the hole portion (52) and the hole portion (53) may be arranged to partially overlap each other when viewed in a planar view.

[0110] In each of the above embodiments, the insulating layer (41) and the insulating layer (42) may be bonded to each other by an adhesive layer. Additionally, the insulating layer (42) and the insulating layer (43) may be bonded to each other by an adhesive layer.

[0111] In each of the above embodiments, the insulating substrate (40) has a structure in which three insulating layers (41, 42 and 43) are stacked. However, the present invention is not limited thereto. For example, the insulating substrate (40) may have a structure in which four or more insulating layers are stacked. For example, the insulating substrate (40) may be implemented with a structure in which four insulating layers are stacked, and the hole portion (53) may be formed to penetrate two insulating layers in the thickness direction.

[0112] In each of the above embodiments, the gas hole (50) is formed as a structure having a single crank shape when viewed in cross-section. However, the shape of the gas hole (50) is not particularly limited. For example, the gas hole (50) may be formed as a structure having two or more crank shapes in succession when viewed in cross-section.

[0113] In each of the above embodiments, the structure of the electrostatic chuck (30) is not particularly limited. For example, the insulating substrate (40) may have a heating element (heater) inside which heat is generated by the application of voltage from outside the substrate fixing device (10) and heating is performed so that the mounting surface (40A) of the insulating substrate (40) reaches a predetermined temperature.

[0114] In each of the above embodiments, the structure of the base plate (20) is not particularly limited. For example, the shape of the gas passage (21) is not particularly limited. In addition, the base plate (20) may be equipped with a heater.

[0115] In each of the above embodiments, the embosses (44) on the substrate surface (40A) may be omitted.

[0116] In each of the above embodiments, the substrate fixing device (10) is applied to a semiconductor manufacturing device, for example, a dry etching device. Examples of dry etching devices include a parallel plate reactive ion etching (RIE) device. Additionally, the substrate fixing device (10) may also be applied to semiconductor manufacturing devices such as a plasma CVD (Chemical Vapor Deposition) device and a sputtering device.

Claims

Claim 1 As an electrostatic chuck, an insulating substrate having a mounting surface on which an adsorbed object is mounted and an opposite surface provided on the opposite side of the mounting surface; and includes a gas hole penetrating from the opposite surface to the mounting surface, wherein the gas hole includes a first hole portion extending from the opposite surface toward the mounting surface, a second hole portion extending from the mounting surface toward the opposite surface, and a third hole portion provided between the first hole portion and the second hole portion and formed to communicate with each other, wherein the first hole portion is provided so as not to overlap with the second hole portion when viewed in a planar view, and the third hole portion has a planar shape larger than the first hole portion and the second hole portion, wherein the first hole portion is provided so that the entire first hole portion overlaps with the third hole portion when viewed in a planar view, and the second hole portion is provided so that the entire second hole portion overlaps with the third hole portion when viewed in a planar view, and the inner circumferential surface of the third hole portion has a first portion and a second portion arranged point-symmetrically with respect to the central axis of the third hole portion. An electrostatic chuck having, wherein the first hole portion is arranged so that a part of the inner circumferential surface of the first hole portion overlaps with the first portion when viewed in a planar view, and the second hole portion is arranged so that a part of the inner circumferential surface of the second hole portion overlaps with the second portion when viewed in a planar view. Claim 2 An electrostatic chuck according to claim 1, further comprising a porous body provided in the third hole portion. Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 An electrostatic chuck according to claim 1 or 2, wherein the insulating substrate has a first insulating layer having the opposite surface, a second insulating layer laminated on the first insulating layer, and a third insulating layer having the mounting surface and also laminated on the second insulating layer, wherein the first hole penetrates the first insulating layer in the thickness direction, the second hole penetrates the third insulating layer in the thickness direction, and the third hole penetrates the second insulating layer in the thickness direction. Claim 7 A substrate fixing device comprising: the electrostatic chuck according to claim 1 or 2; and a base plate bonded to the opposite surface of the electrostatic chuck. Claim 8 delete Claim 9 delete Claim 10 delete

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